TITLE

Relationship Between Varus-Valgus Alignment and Patellar Kinematics in Individuals with Knee Osteoarthritis

AUTHOR(S)
McWalter, Emily J.; Cibere, Jolanda; Maclntyre, Norma J.; Nicolaou, Savvas; Schuizer, Michael; Wilson, David R.
PUB. DATE
December 2007
SOURCE
Journal of Bone & Joint Surgery, American Volume;Dec2007, Vol. 89-A Issue 12, p2723
SOURCE TYPE
Academic Journal
DOC. TYPE
Article
ABSTRACT
Background: Abnormal varus-valgus alignment is a risk factor for patellofemoral osteoarthritis, but tibiofemoral alignment alone does not explain compartmental patellofemoral osteoarthritis progression. Other mechanical factors, such as patellar kinematics, probably play a role in the initiation and progression of the disease. The objective of this study was to determine which three-dimensional patellar kinematic parameters (patellar flex ion, spin, and tilt and patellar proximal, lateral, and anterior translation) are associated with varus and valgus alignment in subjects with osteoarthritis. Methods: Ten individuals with knee osteoarthritis and varus (five subjects) or valgus (five subjects) knee alignment underwent assessment of three-dimensional patellar kinematics. We used a validated magnetic resonance imaging-based method to measure three-dimensional patellar kinematics in knee flexion while the subjects pushed against a pedal with constant load (80 N). A linear random-effects model was used to test the null hypothesis that there was no difference in the relationship between tibiofemoral flex ion and patellar kinematics between the varus and valgus groups. Results: Patellar spin was significantly different between groups (p = 0.0096), with the varus group having 2° of constant internal spin and the valgus group having 4.5° of constant external spin. In the varus group, the patellae tracked with a constant medial tilt of 9.6° with flexion, which was significantly different (p = 0.0056) from the increasing medial tilt (at a rate of 1.8° per 10° of increasing knee flexion) in the valgus group. The patellae of the valgus group were 7.5° more extended (p = 0.0093) and positioned 8.8 mm more proximally (p = 0.0155) than the varus group through the range of flexion that was studied. The pattern of anterior translation differed between the groups (p = 0.0011). Conclusions: Our results suggest that authors of future large-scale studies of the relationships between knee mechanics and patellofemoral osteoarthritis should not rely solely on measurements of tibiofemoral alignment and should assess three-dimensional patellar kinematics directly. Clinical Relevance: Direct measurements of patellar kinematics should be used to investigate links between patellofemoral joint mechanics and the development of patellofemoral osteoarthritis.
ACCESSION #
31710469

 

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